1. Field of the Invention
The present invention relates generally to pulse generators and more particularly to a technique for accurately controlling the pulse repetition interval and pulse width of a pulse generator.
2. Description of the Prior Art
In the electronics industry of today, pulse signal generators are indispensible test instruments used in many manufacturing and engineering applications. They are commercially available from many different sources although not always under the same generic name. Sometimes they are referred to as digital waveform generators, digital synthesizers, or pulse generators. Although commercial generators vary somewhat in the features offered, most models have the capability of producing pulse waveforms of variable pulse width (PW) and variable pulse repetition interval (PRI), and most have an accuracy to .+-. a few percent. Many can accurately control the pulse width or the pulse repetition interval, but not both with high precision and stability. Unfortunately a high degree of precision and stability is often required by specific applications. A few commercial pulse generators have crystal controlled time bases to regulate the accuracy of the PRI but not the pulse width.
The subject invention overcomes these drawbacks by employing a stabilization technique for locking both the PRI and pulse width of a digital signal to a highly stable clock signal, such as a crystal controlled oscillator.
An object of this invention is the provision of a pulse waveform generator capable of producing a pulse waveform having an adjustable PRI and pulse width both locked to a ultra stable clock signal.
Still another object of this invention is the provision of a pulse waveform generator capable of producing a pulse waveform having a pulse repetition interval and a pulse width which can be independently programmed at any time by two separate control signals to an accuracy determined by the time base of the reference clock oscillator.